In recent years, the method of contactlessly supplying electrical energy to wireless power receivers in a wireless manner has been used instead of the traditional method of supplying electrical energy in a wired manner. The wireless power receiver that receives energy in a wireless manner may be directly driven by the received wireless power, or a battery may be charged by using the received wireless power, then allowing the wireless power receiver to be driven by the charged power.
For allowing smooth wireless power transfer between a wireless power transmitter which transmits power in a wireless manner and a wireless power receiver which receives power in a wireless manner, the standardization for a technology related to the wireless power transfer is undergoing.
As part of the standardization of wireless power transmission technology, the Wireless Power Consortium (WPC) which deals with magnetic inductive wireless power transmission technology disclosed a standards document “System description Wireless Power Transfer, Volume 1, Low Power, Part 1: Interface Definition, Version 1.00 Release Candidate 1 (RC1)” for interoperability in the wireless power transfer on Apr. 12, 2010.
Established in March, 2012, Power Matters Alliance, another technology standards consortium, disclosed a standards document based on inductive coupling technology to advance a suite of interface standards and provide inductive and resonant power.
Wireless charging using electromagnetic induction is often used in our daily life. Commercial applications of wireless charging using electromagnetic induction are toothbrushes and wireless coffee pots, for example.
Recently, there is a growing demand for one-to-many charging, evolving from one-to-one charging. To meet this demand, a variety of methods of communication between one wireless power transmitter and multiple wireless power receivers are being presented with respect to one-to-many charging.